Some refrigeration systems use a single compressor to serve a plurality of evaporator circuits, i.e., supermarket freezer and refrigerator sections, office building air conditioning, etc., where the cooling capability is distributed to the plurality of evaporator circuits. These systems require a refrigerant distributor assembly configured to properly apportion the cooling capacity of the refrigerant to the plurality of evaporator circuits. Ordinarily, refrigerant separates unevenly for two reasons. First, refrigerant is predominantly liquid by weight, but vapor occupies most of the volume, and second liquid and vapor flow at different velocities. FIGS. 1A–1C illustrate typical refrigerant flow for three common orientations of a system having a simple header, without benefit of a refrigerant distributor.
Today, refrigeration distributors use a fixed orifice that is pre-chosen when the system is designed. The orifice acts as a nozzle, creating a pressure drop across the nozzle and a turbulence in the refrigerant so that each of the plurality of evaporator circuits ideally receives a uniform amount of the refrigerant. The orifice size is chosen during design of the system using such factors as, type of refrigerant, size of the system, capacity of the system, or liquid temperature at the expansion valve, etc.
When multiple heat exchanger refrigeration systems are installed, a high percentage, but not all, of the installations have what can be considered to be the correct size orifice. Of course, that means that a fair percentage of installations do not have the proper size orifice. If the installed system is incorrect, i.e., the pressure drop across the nozzle is not as planned, the system must be opened, the distributor disassembled, and a new orifice installed to create a different pressure drop. This is both time consuming and costly. However, even if an orifice is correct for warm/hot summer conditions, when it is winter and the liquid temperature is significantly colder, a smaller orifice is needed but is not present. To partially compensate for these varying conditions, a very restrictive orifice is generally chosen at the higher summer temperature, and the system designer/installer hopes that the refrigerant feed to the plurality of evaporator circuits will be suitable during winter conditions. Furthermore, if a new refrigerant were to be made available or mandated, the system would have to be opened and a suitable orifice installed for the new refrigerant. The only other known refrigerant distributor uses an interior body sculpted to create turbulence in the distributor, and is not adjustable.
Accordingly, what is needed in the art is a distributor assembly that enables the distributor to be adjusted for changing conditions without opening the refrigeration system.